SPECTROSCOPIC STUDIES OF RARE EARTH IONS DOPED GLASSES FOR PHOTONIC APPLICATIONS

Abstract

In this thesis, we have examined the structural, optical and photoluminescence characteristics of rare earth (RE) doped glasses. Glasses are emerging as better candidate for the doping of RE ions for wide range of applications in the fields of white light emitting diode (w-LEDs), solid state lasers, sensors and optical amplifiers, etc. They are sustainable and holds wide emission as well as homogeneous emission characteristics. Glasses can be synthesized by simple technique and they possess high thermal and mechanical sustainability with minimum manufacturing charges. Incorporation of alkali and alkaline metal oxides enhances its durability and emission probabilities of the host glass system. Further addition of RE ions increases utility in photonic applications. Visualizing these facts, the aim of this research work is to explore the effect of RE ions doping on structural and spectroscopic properties of borosilicate glasses. In the present work lithium lead zinc alumino borosilicate (LPZABS) glasses have been prepared by melt quench technique doped with RE ions like Sm3+, Dy3+ and Sm3+/Eu3+ through different concentrations of these RE ions and studied their structural and photoluminescence properties to understand their usage in photonic device applications. The glassy nature and functional groups present in the host glass has been confirmed by recording XRD and FT-IR spectral features. The experimentally measured physical properties such as density (Archimedes principle) and refractive index (Brewster’s angle method) were used to compute many other physical properties of the titled glasses. Spectroscopic analysis was done on the basis of absorption, excitation, emission and decay recordings. Five chapters of this thesis consists of literature survey, manufacturing technique and characterization of the titled glass samples. Chapter 1: This chapter consists of brief introduction to origin and history of glasses. Different glasses with its components, formation and properties are studied. Electronic viii transitions, optical parameters, energy transfer in RE ions and selection of the host glass system are explained. Along with this, recent developments and encouragement to pursue research in the field of glasses has been discussed in detail. Chapter 2: In this chapter synthesis and characterization techniques for the present glass system have been incorporated in detail. Chapter 3: It describes an intense orange color emitting Sm3+ activated LPZABS glasses which were propitiously fabricated by using sudden quenching method to study the luminescent potentiality using spectroscopic techniques such as XRD, FT-IR, optical absorption, photoluminescence (PL) and PL decay. XRD and FT-IR reveals the glassy nature and various functional groups present in LPZASB host glass respectively. Judd Ofelt parameters derived from absorption spectra are used to estimate various radiative parameters for the excited states of Sm3+ ions in LPZASB glasses. Under 400nm excitation, the luminescence spectra in the as prepared glasses exhibit three emission bands that corresponds to 4G5/2→6H5/2 (562 nm), 4G5/2→6H7/2 (598 nm) and 4G5/2→6H9/2 (645 nm) transitions of Sm3+ ions. Among these three, 4G5/2→6H9/2 transition observed in orange region (598 nm) is relatively more intense and prominent. The PL decay curves recorded for 4G5/2 fluorescent level reveal exponential behavior and single exponential fitting is applied to evaluate the experimental lifetimes ( ). The values are found to be decreasing with Sm3+ ion content due to cross-relaxation energy transfer process. The results reveal that the as prepared glasses can be effectively used in fabricating intense visible orange color emitting optoelectronic devices. (Part of this chapter is published in Optical Materials).